Brabham BT49 - Chassis and Suspension

Chassis and Suspension

Like all of its Formula One contemporaries, the BT49 chassis is a monocoque structure. It is built from sheet aluminium alloy with reinforcement from carbon fibre composite panels and is one of the first Formula One chassis to incorporate this material structurally. The chassis is slightly longer than that of the BT48, and is new from the cockpit back with revised sidepods and a structural fuel tank reduced from 45 to 38 imperial gallons (205 to 173 L) capacity to match the reduced fuel consumption requirements of the DFV compared to the Alfa Romeo. This allowed a reduction in dry weight over the BT48 of 35 pounds (15.9 kg) and of 95 lb (43.1 kg) when fully fuelled.

The underside of the BT49 is shaped to create downforce through ground effect: air is accelerated under the car, reducing the air pressure beneath it and pushing the tyres down harder onto the track. This provides more grip and thus higher cornering speeds, but compared to conventional wings creates less of the drag that slows the car in a straight line. In its original form, the reduced pressure area under the car was sealed off with sliding skirts which rose and fell with the movement of the car to ensure no air could leak under it. According to Murray, the aerodynamics were the car's great strength: "It had more than any other car and it all came from the ground effect. We ran the car with no front wing at all and scarcely any at the back."

The suspension, which controls the relative motion of the chassis and the wheels, is similar to that of the BT48: it features double wishbones front and rear, with the springs and dampers mounted on the chassis out of the airflow and activated by pullrods. Anti-roll bars are fitted front and rear. The BT49's disc brakes are mounted outboard, within the wheel hubs, and are activated by a single four piston brake caliper for each wheel. For most of the BT49's career, it used conventional steel brakes. Lighter reinforced carbon-carbon discs and pads, a technology that Brabham had introduced to Formula One in 1976, were used in 1981 and 1982; The wheels are of 13-inch (330 mm) diameter, although occasionally 15 in (381 mm) wheels were used at the front. The car initially raced on Goodyear tyres, but the team had to adapt the BT49 to Michelin's new radial tyres for part of the 1981 season when Goodyear temporarily withdrew from Formula One. Slick tyres were used in dry conditions and treaded tyres in the wet.

Three chassis, included the two modified BT48 units, were built for the end of the 1979 season. Two of these were re-used during the 1980 Formula One season, alongside seven new chassis.